fix legend values when value is undefined

+ improve mechanism to find value

seaweb.py

@@ -57,6 +57,7 @@ def to_json_sse(msg):
 app = flask.Flask(__name__)
 
 update_rider = circularlog.Rider("upd")
+pollinterval = 0.1
 
 @app.route('/update')
 def get_update(path=None):
@@ -82,7 +83,7 @@ def get_update(path=None):
                     yield to_json_sse(msg)
                 if messages:
                     lastmsg = time.time()
-                    gevent.sleep(1)
+                    gevent.sleep(pollinterval)
                 else:
                     if time.time() > lastmsg + 30:
                         if not client.info():
@@ -91,7 +92,7 @@ def get_update(path=None):
                         yield to_json_sse(dict(type='heartbeat'))
                         lastmsg = time.time()
                     else:
-                        gevent.sleep(0.5)
+                        gevent.sleep(pollinterval)
         except (GeneratorExit, tcp_lineserver.Disconnected) as e:
             logging.info("except clause %r", repr(e))
             logging.info('CLOSED %s', client.id)